ABSTRACT
L-arabinose isomerase (L-AI) can isomerize L-arabinose and D-galactose into L-ribulose and D-tagatose, respectively, which is currently the most effective biological catalyst for D-tagatose production. The crystal structure of L-AI has been solved recently and its gene has been cloned, sequenced and overex- pressed. L-AI improved by protein engineering will be the dominant enzyme for industrial production of D-tagatose. This paper reviewed researches on protein structure and function, properties and application in D-tagatose production of L-AI, and the long-term potential development of L-AI was prospected.
ABSTRACT
An extracellar fibrinolytic strain was isolated from fermented shrimp paste. In addition to general physiological and biochemical properties, the strain was identified by 16S rDNA sequence and systematic analysis. The results showed that 16S rDNA sequence of the strain had high similarity with AY601723 and AB195282, suggesting that the strain is a subspecies of Bacillus sp. It was named as Bacillus sp. nov. SK006 by CCTCC. The medium composition and fermentation conditions for fibrinolytic enzyme production were also optimized in the research.
ABSTRACT
Thermostable L-arabinose isomerase (L-AI) is the most potential enzyme for the biological production of D-tagatose from D-galactose, a novel functional factor. Gene araA encoding the L-arabinose isomerase from Bacillus stearothermophilis IAM 11001 was cloned and expressed in Escherichia coli. The araA gene of 1491 bp has 95% identity with L-AI from Thermus sp. IM6501. The GenBank accession number for the nucleotide sequence of this araA gene determined in this work is EU394214.The bacterium was induced by IPTG and analyzed by SDS-PAGE, approximately 59 kDa exogenous protein was observed on the SDS-PAGE. The recombinant L-AI was purified to electrophoretical homogeneity with affinity chromatography, and the activity of recombinant L-AI was also studied. The bioconversion rate of D-galactose to D-tagatose reached 39.4% after 24h whole cell reaction.
ABSTRACT
Rare sugars were defined as monosaccharides and their derivatives that rarely exist in nature. They played an important role in food, health, medicine and etc A strategy for bioproduction of rare sugars, namely Izumoring, was described. By the Izumoring method, all monosaccharides and polyols could be linked, using enzymatic reaction with D-tagatose 3-epimerase, aldose isomerases and polyol dehydrogenases. Izumoring for hexoses, pentoses and tetroses were designed respectively. According to this strategy, the bioproduction routes of various rare sugars, using microbial and enzymatic reactions, could be obtained. In addition, the future research tendency of biotransformation of rare sugars was put forward.
ABSTRACT
To investigate the structure disruption of BSA (1mg/ml, dissolved in PBS) induced by ultrasonication and the French press. The BSA solution was passed through the French press and received ultrasound irradiation, and then detected by HPLC(High-performance liquid chromatography),DLS(Dynamic Light Scattering),CD(Circular Dichroism)and nondenaturing SDS-PAGE. Detection results showed that BSA was polymerized after ultrasound irradiation and the polymerization can be reduced by adding mannitol (free radical scavenger). This means that the free radical play an important role in this process. However, the BSA passing through the French press for several times wasn’t polymerized, and the secondary structure was somewhat destroyed. These results suggested that ultrasound irradiation and French press destroy the molecular structure in different manners, so that the suitable cell lyses methods should be selected according to the characteristics of the protein.